Statistics (Chapter 3)

A chapter from my class online textbook, “SticiGui” by Philip B. Stark and the University of Berkeley’s Department of Statistics.

Statistics examines data and the ways to measure it, using case studies as tools, video segments from the classroom, various interactive charts (called histograms), and quizzes with solutions. The quizzes are very effective to ensure that what you learn in text and video, is reinforced to make it easier to remember.

This chapter’s summary states:

“This chapter introduced variables, and distinctions among variables, according to the kinds of values the variables can take: quantitative, qualitative, and categorical. Quantitative variables are classified further as either discrete or continuous. Data—observed values of variables—can be presented in many ways. Tables often are easier to understand than words. When the number of data is large, looking at the data provides little insight, but summaries of the data can help. Quantitative data can be summarized using frequency tables. Constructing a frequency table requires specifying class intervals and an endpoint convention. Frequency tables can be presented graphically as histograms, which give an impression of the distribution of the data. In a histogram, relative frequency is represented by area. Characteristics of the distribution that can be gleaned from a histogram include symmetry, skewness, and the number and location of modes. However, the appearance of those characteristics in a histogram depends on the number and location of the class intervals. Percentiles are another way to summarize the distribution of a list. Calculating percentiles exactly requires the original data, but percentiles can be estimated approximately from histograms.”

Easy to follow, though it does take a little while to go through the entire chapter (though no longer than any textbook), this textbook makes learning fun and engaging – a hard thing, when it comes to the mathematically challenged (aka – me!).